Biocontrol potential of Cladosporium sphaerospermum against the wheat powdery mildew fungus Blumeria graminis f. sp. tritici.

Cladosporium spp. are known to be mycoparasites and inhibit phytopathogenic fungi. However, so far, little information is available on the impacts of Cladosporium spp. on powdery mildews. Based on the morphological characteristics and molecular analysis, C. sphaerospermum was identified as a mycoparasite on the wheat powdery mildew fungus (Blumeria graminis f. sp. tritici, Bgt, recently named as B. graminis s. str.). C. sphaerospermum was capable of preventing colony formation and conidial distribution of Bgt. The biomasses of Bgt notably decreased by 1.3, 2.2, 3.6 and 3.8 times at 2 dpi, 4 dpi, 6 dpi and 8 dpi, respectively. In addition, biomasses of C. sphaerospermum at 2 dpi, 4 dpi, 6 dpi and 8 dpi significantly increased to 5.6, 13.9, 18.2 and 67.3 times, respectively. In vitro, C. sphaerospermum exudates significantly impaired appressorial formation of Bgt. Thus, C. sphaerospermum acts as a potential biological control agent by suppressing the formation, distribution and development of Bgt conidia and is a viable alternative for managing the wheat powdery mildew. These results suggest that C. sphaerospermum is an antagonistic parasite of the wheat powdery mildew fungus, and hence, provide new knowledge about the biological control of phytopathogenic fungi.

Efficient recombinant production of mouse-derived cryptdin family peptides by a novel facilitation strategy for inclusion body formation.

BACKGROUND: A number of antimicrobial peptides (AMPs) hold promise as new drugs owing to their potent bactericidal activity and because they are often refractory to the development of drug resistance. Cryptdins (Crps) are a family of antimicrobial peptides found in the small intestine of mice, comprising six isoforms containing three sets of disulfide bonds. Although Crp4 is actively being investigated, there have been few studies to date on the other Crp isoforms. A prerequisite for detailed characterization of the other Crp isoforms is establishment of efficient sample preparation methods. RESULTS: To avoid degradation during recombinant expression of Crps in E. coli, co-expression of Crps with the aggregation-prone protein human α-lactalbumin (HLA) was used to promote the formation of stable inclusion bodies. Using this method, the production of Crp4 and Crp6 by the BL21 strain was effective, but the expression of other Crp isoforms was not as efficient. The results of a cell-free system study suggested that Crps were degraded, even though a substantial amounts of Crps were synthesized. Therefore, using the Origami™ B strain, we were able to significantly increase the expression efficiency of Crps by promoting the formation of erroneous intermolecular disulfide bonds between HLA and Crps, thereby promoting protein aggregation and inclusion body formation, which prevented degradation. The various Crp isoforms were successfully refolded in vitro and purified using reversed-phase HPLC. In addition, the yield was further improved by deformylation of formyl-Crps. We measured the antibacterial activity of Crps against both Gram-positive and Gram-negative bacteria. Each Crp isoform exhibited a completely different trend in antimicrobial activity, although conformational analysis by circular dichroism did not reveal any significant steric differences. CONCLUSION: In this study, we established a novel and efficient method for the production of the cryptdin family of cysteine-containing antimicrobial peptides. Additionally, we found that there were notable differences in the antibacterial activities of the various Crp family members. The expression system established in this study is expected to provide new insights regarding the mechanisms underlying the different antibacterial activities of the Crp family of peptides.

Potent bactericidal activity of reduced cryptdin-4 derived from its hydrophobicity and mediated by bacterial membrane disruption.

Defensin is a cysteine-rich antimicrobial peptide with three disulphide bonds under normal oxidative conditions. Cryptdin-4 (Crp4) is a defensin secreted by Paneth cells in the small intestine of mice, and only reduced Crp4 (Crp4red) shows activity against enteric commensal bacteria, although both oxidised Crp4 (Crp4ox) and Crp4red can kill non-commensal bacteria. To investigate the molecular factors that affect the potent antimicrobial activity of Crp4red, the bactericidal activities of Crp4ox and Crp4red, Crp4 with all Cys residues substituted with Ser peptide (6C/S-Crp4), and Crp4 with all thiol groups modified by N-ethylmaleimide (NEM-Crp4) were assessed. All peptides showed bactericidal activity against non-commensal bacteria, whereas Crp4red and NEM-Crp4 showed bactericidal activity against commensal bacteria. These potent peptides exhibited high hydrophobicity, which was strongly correlated with membrane insertion. Intriguingly, Crp4ox formed electrostatic interactions with the membrane surface of bacteria, even without exerting bactericidal activity. Moreover, the bactericidal activity of both oxidised and reduced forms of Crp4 was abolished by inhibition of electrostatic interactions; this finding suggests that Crp4red targets bacterial membranes. Finally, a liposome leakage assay against lipids extracted from commensal bacteria demonstrated a correlation with bactericidal activity. These results suggest that the potent bactericidal activity of Crp4red is derived from its hydrophobicity, and the bactericidal mechanism involves disruption of the bacterial membrane. Findings from this study provide a better understanding of the bactericidal mechanism of both Crp4ox and Crp4red.

Coronavirus Disease 19 Infection Does Not Result in Acute Kidney Injury: An Analysis of 116 Hospitalized Patients from Wuhan, China.

BACKGROUND: Whether the patients with coronavirus disease 19 (COVID-19) infected by severe acute respiratory syndrome (SARS)-CoV-2 would commonly develop acute kidney injury (AKI) is an important issue worthy of clinical attention. This study aimed to explore the effects of SARS-CoV-2 infection on renal function through analyzing the clinical data of 116 hospitalized COVID-19-confirmed patients. METHODS: One hundred sixteen COVID-19-confirmed patients enrolled in this study were hospitalized in the Department of Infectious Diseases, Renmin Hospital of Wuhan University from January 14 to February 13, 2020. The recorded information includes demographic data, medical history, contact history, potential comorbidities, symptoms, signs, laboratory test results, chest computer tomography scans, and treatment measures. SARS-CoV-2 RNA in 53 urine sediments of enrolled patients was detected by real-time reverse transcription-polymerase chain reaction. RESULTS: Twelve (10.8%) patients showed mild increase of blood urea nitrogen or creatinine (<26 µmol/L within 48 h), and 8 (7.2%) patients showed trace or 1+ albuminuria in 111 COVID-19-confirmed patients without chronic kidney disease (CKD). All these patients did not meet the diagnostic criteria of AKI. In addition, 5 patients with CKD who were undergone regular continuous renal replacement therapy (CRRT) before admission were confirmed infection of SARS-CoV-2 and diagnosed as COVID-19. In addition to therapy for COVID-19, CRRT was also applied 3 times weekly during hospitalization for these 5 patients with CKD. In the course of treatment, the renal function indicators showed stable state in all 5 patients with CKD, without exacerbation of CKD, and pulmonary inflammation was gradually absorbed. All 5 patients with CKD were survived. Moreover, SARS-CoV-2 RNA in urine sediments was positive only in 3 patients from 48 cases without CKD, and 1 patient had a positive for SARS-CoV-2 open reading frame 1ab from 5 cases with CKD. CONCLUSION: AKI was uncommon in COVID-19. SARS-CoV-2 infection does not result in AKI, or aggravate CKD in the COVID-19 patients.

Antimicrobial Properties and Mode of Action of Cryptdin-4, a Mouse α-Defensin Regulated by Peptide Redox Structures and Bacterial Cultivation Conditions.

Cryptdin-4 (crp4) is an enteric α-defensin derived from mice, and is a main mediator of immunity to oral infections and a determinant of the composition of the intestinal microbiota. Structurally, crp4 exists in two states: the oxidized form (crp4oxi), constrained by three invariant disulfide bonds, and the reduced form (crp4red) with six free thiol groups, both of which exist in the intestinal tract. In this study, the antibacterial mechanisms of crp4 in both forms under aerobic and anaerobic conditions were investigated using Escherichia coli (E. coli), an anaerobic facultative bacterium, as a model. Fluorescent dye studies revealed that both crp4oxi and crp4red exhibited antimicrobial activity against cells cultured under aerobic conditions via rapid membrane depolarization. Furthermore, the antioxidant treatment experiments suggested that only crp4oxi exhibited antimicrobial activity by the induction and accumulation of reactive oxygen species (ROS). However, under anaerobic culture conditions, the ability of both forms to disrupt the function of bacterial membranes decreased and activity was greatly reduced, but crp4red maintained some antimicrobial activity. This activity may be due to the inhibition of intracellular functions by DNA binding. Altogether, these data indicate that, according to its redox structure and the environmental redox conditions, crp4 could perform different antimicrobial activities via different mechanisms.

[Expression and subcellular localization of APOBEC3G in peripheral blood mononuclear cells and liver tissues of chronic HBV patients].

OBJECTIVE: To study the expression level and intracellular localization of APOBEC3G in peripheral blood mononuclear cells (PBMCs) and liver tissues of chronic HBV patients. METHODS: The expression level and intracellular localization of APOBEC3G in PBMCs and liver tissues were detected using the western blot and confocal laser scanning microscope (CLSM). RESULTS: Western-blot showed that the expression level of APOBEC3G in PBMCs of healthy controls was very low. The relative expression levels of APOBEC3G in PBMC of patients with chronic hepatitis B, chronic severe hepatitis, liver cirrhosis, or liver cancer were 4.12+/-0.21, 4.07+/-0.28, 4.16+/-0.36 or 4.21+/-0.39 respectively, which were higher than that in the healthy controls. However, there was no significant difference in APOBEC3G expression among different chronic HBV patients (q = 0.931, 0.744, 1.675, 1.675, 2.606 or 0.931, respectively, all P values more than 0.05). In addition, there was no significant difference on APOBEC3G in liver tissues between chronic hepatitis B patients and hepatocellular carcinoma patients (4.40+/-0.34 vs 4.34+/-0.43, q = 0.588, P more than 0.05). CLSM indicated that the localization of APOBEC3G protein was in cytoplasm of PBMCs and hepatocytes. CONCLUSION: APOBEC3G is upregulated in the PBMCs of chronic hepatitis B patients.

Clinical characteristics of 25 death cases with COVID-19: A retrospective review of medical records in a single medical center, Wuhan, China.

OBJECTIVES: This study aims to summarize the clinical characteristics of death cases with COVID-19 and to identify critically ill patients of COVID-19 early and reduce their mortality. METHODS: The clinical records, laboratory findings and radiological assessments included chest X-ray or computed tomography were extracted from electronic medical records of 25 died patients with COVID-19 in Renmin Hospital of Wuhan University from Jan 14 to Feb 13, 2020. Two experienced clinicians reviewed and abstracted the data. RESULTS: The age and underlying diseases (hypertension, diabetes, etc.) were the most important risk factors for death of COVID-19 pneumonia. Bacterial infections may play an important role in promoting the death of patients. Malnutrition was common to severe patients. Multiple organ dysfunction can be observed, the most common organ damage was lung, followed by heart, kidney and liver. The rising of neutrophils, SAA, PCT, CRP, cTnI, D-dimer, LDH and lactate levels can be used as indicators of disease progression, as well as the decline of lymphocytes counts. CONCLUSIONS: The clinical characteristics of 25 death cases with COVID-19 we summarized, which would be helpful to identify critically ill patients of COVID-19 early and reduce their mortality.

Effects of cell cycle on telomerase activity and on hepatitis B virus replication in HepG2 2.2.15 cells.

BACKGROUND: It has been shown that telomerase activity and hepatitis B virus (HBV) replication are closely associated with cell cycle. This study aimed to further investigate the effects of cell cycle on telomerase activity and on HBV replication. METHODS: Human hepatoma cells transfected with HBV DNA (HepG2 2.2.15 cell line) were treated respectively with serum deprivation, all-trans retinoic acid (RA), dimethyl sulfoxide (DMSO), or sodium butyrate. The cell cycle of HepG2 2.2.15 cells was analyzed by flow cytometry. The telomerase activities of the cells were detected by TRAP-PCR-ELISA. HBV DNA in culture medium was assayed by a fluorescent quantitative PCR assay and a semiquantitative dot blot hybridization technique. HBsAg and HBeAg in culture media were quantitatively examined by an ELISA assay. RESULTS: Treatments with serum deprivation, RA, DMSO, or sodium butyrate inhibited the proliferation of HepG2 2.2.15 cells and led to cell arrest in the G0/G1 phase of cell cycle. The percentage of the G0/G1 phase in the groups of sodium butyrate, DMSO, RA and serum-free was 85.2%, 71.9%, 68.3% and 65.2%, respectively, but in the control group, 43.1% (P<0.01). The activities of telomerase of the cells were also significantly inhibited by 82.8%, 74.6%, 76.1% and 69.4% respectively. In addition, HBV replication of the HepG2 2.2.15 cells remarkably increased as shown by the contents of HBV DNA, HBsAg and HBeAg in the culture media of the cells treated with sodium butyrate, DMSO, RA or serum deprivation (P<0.01). The amounts of HBV DNA in the groups of sodium butyrate, DMSO, RA, serum deprivation and control were 6.7X10(6), 4.8X10(6), 4.4X10(6), 5.1X10(6) and 1.2X10(6) copies/ml, respectively (P<0.01). Telomerase was expressed mainly in the cells in S phase. HBV replication increased in quiescent cells (G0/G1 phase), and decreased in proliferating phase (S phase). CONCLUSION: The current data approve that HBV replication is associated with the cellular proliferative activity.

Effects of S-adenosylmethionine on liver methionine metabolism and steatosis with ethanol-induced liver injury in rats.

BACKGROUND: Hyperhomocysteinemia is implicated in the pathogenesis of various liver diseases. In this study, the effects of S-adenosylmethionine (SAM) on hyperhomocysteinemia and steatosis with ethanol-induced liver injury in rats were examined and their mechanisms were explored. METHODS: Forty-eight female Sprague-Dawley rats were randomly divided into four groups as control, model, low-dose, and high-dose SAM groups. Except the control group, all rats were fed high-fat-containing diet plus ethanol and fish oil gavaged for 8 weeks. SAM was administered by intraperitoneal injection after the 4 weeks' exposure of ethanol. Serum homocysteine (Hcy), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), triglyceride (TG), tumor necrosis factor alpha (TNF-alpha), and transforming growth factor beta1 (TGF-beta1) levels were determined. The contents of liver malondialdehyde (MDA) and glutathione (GSH) were assayed. Liver histology was also examined. The expressions of TNF-alpha and TGF-beta1 mRNAs in the liver were detected by the reverse transcriptase-polymerase chain reaction assay. RESULTS: Compared with the control group, the model group rats developed marked liver damage, accompanied by an increase in Hcy, ALT, AST, TC, TG, TNF-alpha, TGF-beta1, and MDA levels. However, the levels of GSH were decreased. These responses were associated with the increased expression of TNF-alpha and TGF-beta1 mRNAs in the livers, as well as the existence of hepatocellular necrosis and neutrophil infiltration in the livers. In treatment groups, SAM provided significant protection from the liver injury induced by alcohol, resulting in a decrease in serum TNF-alpha, TGF-beta1 levels, lipid peroxidation, and the expressions of TNF-alpha and TGF-beta1 mRNAs in the livers, as well as an increase in GSH levels. However, no statistical difference was observed in these parameters between the two different dose treatment groups. In the study, SAM did not affect plasma total homocysteine (tHcy) levels significantly. CONCLUSION: SAM prevents alcohol-induced liver injury in rats by reducing liver lipid peroxidation, anti-inflammation, and antihyperplasia. In addition, it does not affect the plasma tHcy levels.

[Effect of cell cycle on telomerase activity of hepatoma cells and its relationship with replication of hepatitis B virus].

BACKGROUND & OBJECTIVE: Previous studies have shown that the expression of telomerase activity is closely correlated with the formation and development of tumor cells. Furthermore, the cell cycle is associated with hepatitis B virus (HBV) replication level and telomerase activity. For further study their relationship, this experiment was designed to investigate the effect of serum deprivation or all-trans-retinoic acid(RA)on cell cycle of human hepatoma cells transfected by HBV DNA (HepG2 cell line) and the associations of cell cycle with telomerase activity and HBV replication. METHODS: Human hepatoma HepG2 cells were respectively treated with serum deprivation or RA. Cell cycle was analyzed using flow cytometry. Telomerase activity was determined quantitatively by TRAP-PCR-ELISA. HBV-DNA in culture media was determined using quantitative PCR and semiquantitative dot blot hybridization assay. HBsAg and HBeAg in cell culture media were measured using quantitative ELISA. RESULTS: RA treatment or serum deprivation inhibited the proliferation of HepG2 cells and the cells were arrested at G(0)/G(1) phase. The percentages of G(0)/G(1) phase of RA group and serum deprivation were 68.3% and 65.2%, respectively, while that of control group was 43.1% (P< 0.01). The levels of telomerase activity also significantly decreased. The absorbance values that represented the telomerase activity of RA group and serum deprivation group were 0.32 and 0.41, respectively, while that of control group was 1.34(P< 0.01). In addition,HBV replication of HepG2 cells remarkably increased, which was shown as high products of HBV-DNA, HBsAg and HBeAg in culture media of RA group and serum deprivation group. The contents of HBV DNAs were 4.4x10(6), 5.1x10(6), and 1.2x10(6) copies/ml in RA group, serum deprivation group, and control group, respectively(P< 0.01). The values of P/N of HBsAg were 3.5, 3.7, and 1.3 in RA group, serum deprivation group, and control group, respectively (P< 0.01). The values of P/N of HBeAg were 19.8, 22.5, and 13.4 in RA group, serum deprivation group, and control group, respectively (P< 0.01). CONCLUSION: Telomerase expression was associated with cell cycle in HepG2 cells. Telomerase was mainly expressed in S phase of cell cycle. HBV replication was also closely correlated with cell cycle, which increased in quiescent hepatocytes and decreased in proliferating hepatocytes.